1. Field of the Invention
The present invention relates to an analog-to-digital converter (ADC), and more particularly, to a time-interleaved ADC and a self-calibration method thereof.
2. Description of the Prior Art
An analog-to-digital converter (ADC) is a commonly seen circuit element, which can convert an input signal of an analog format into an output signal of a digital format and has an extensive range of application. For example, the ADC can be applied in an analog front end of various communication systems. For a flash ADC or a flash-like ADC such as a folding ADC, in order to increase the operation speed, a plurality of sub-ADCs, connected in parallel and each performing a sampling operation by utilizing one of a plurality of clock signals with different phases, are usually adopted to form a single time-interleaved ADC. theoretically speaking, the more the sub-ADCs are included in the time-interleaved ADC, the faster the operation speed of the time-interleaved ADC will be.
Although the time-interleaved ADC can provide a faster signal converting speed, there will be presented some problems due to multiple sub-ADC nature of the time-interleaved ADC. For example, there will be the timing skew problem among the plurality of sub-ADCs, and the existence of gain mismatch and/or offset mismatch among the plurality of sub-ADCs caused by the factors such as fabrication process variation will also become a problem that needs to be overcome when designing the time-interleaved ADC.